On 6/8/24 05:36, Yosry Ahmed wrote:
> diff --git a/mm/zswap.c b/mm/zswap.c
> index b9b35ef86d9be..ebb878d3e7865 100644
> --- a/mm/zswap.c
> +++ b/mm/zswap.c
> @@ -1557,6 +1557,26 @@ bool zswap_load(struct folio *folio)
>
> VM_WARN_ON_ONCE(!folio_test_locked(folio));
>
> + /*
> + * Large folios should not be swapped in while zswap is being used, as
> + * they are not properly handled. Zswap does not properly load large
> + * folios, and a large folio may only be partially in zswap.
> + *
> + * If any of the subpages are in zswap, reading from disk would result
> + * in data corruption, so return true without marking the folio uptodate
> + * so that an IO error is emitted (e.g. do_swap_page() will sigfault).
> + *
> + * Otherwise, return false and read the folio from disk.
> + */
> + if (folio_test_large(folio)) {
> + if (xa_find(tree, &offset,
> + offset + folio_nr_pages(folio) - 1, XA_PRESENT)) {
> + WARN_ON_ONCE(1);
> + return true;
> + }
How does that work? Should it be xa_find_after() to not always find
current entry?
And does it still mean those subsequent entries map to same folio?
--Mika
